A. Field of the Invention
This invention relates to testing apparatus and methds of operation. More particularly, the invention relates to testing and processes of testing complex semiconductor components including logic and analog functions.
B. Description of the Prior Art
Traditionally, semiconductor components include either analog or digital functions, but not both types of functions. Testing of analog functions generally requires complex stimulus signals such as provided by pulse generators, function generators, frequency synthesizers, and the like. Similarly, complex measurement apparatus such as capacitance meters, gain/phase meters, waveform analyzers, and the like, are required to test the component incorporating analog functions.
Digital logic functions, in contrast, simply require sequences of binary 1's and 0's or bit patterns to test the digital function in a component. The digital response is compared to an expected response to verify the function.
Computer operated test apparatus for digital and analog functions, as represented by U.S. Pat. No. 3,492,572 and Hewlitt Packard network analyzer (HP) 3042A or 8507A and the like, respectively, subject a component to a sequence of tests under program control. Such testers are also conditioned to vary the tests according to the component to be tested.
Integrated circuit technology, particularly large scale integration, is moving in the direction to incorporate both analog and digital functions in the same component. In particular, monolithic circuits for driving displays require logic functions for selection and analog functions for driving the displays. Testing of components incorporating digital and analog functions is time-consuming and expensive where separate logic and analog testers are utilized. The combination of an analog and digital tester under computer control in a single test apparatus is not a straight-forward engineering exercise. A number of problems must be overcome to merge a digital and analog tester in a single test apparatus. Among these problems are impedance matching a plurality of stimulus/measurement units to a plurality of semiconductor products. Another problem is adapting the tester to appropriately AC and DC load, a variety of semiconductor products without impacting the performance of the product. Stated another way, an analog/logic tester must be arranged to test a variety of semiconductor products without affecting the performance of the product or the capacity of the tester to conduct the various tests. There are testers for digital-to-analog and analog-to-digital components, as evidenced by U.S. Pat. No. 3,816,813 issued June 11, 1974, but such testers are not adapted to perform a variety of digital and analog tests as required by operational amplifiers, oscillators, combinatorial and sequential logic circuits. There are also testers that include adapter cards for providing different test conditions to a digital component, as described in U.S. Pat. No. 3,622,876. Such testers do not match tester and component impedance, for a variety of digital and analog tests and a range of components.